Mosfet bias.
- pre65
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#1 Mosfet bias.
I need a 4.7v bias for the mosfet amp.
Is that + 4.7v ?
I was thinking of using a 4.7v zener diode, but I see there are several through hole types. What level of current (ma) is involved ?
OR, an LM329 fixed voltage ref (6.9v) and a trim pot ?
Is that + 4.7v ?
I was thinking of using a 4.7v zener diode, but I see there are several through hole types. What level of current (ma) is involved ?
OR, an LM329 fixed voltage ref (6.9v) and a trim pot ?
The only thing necessary for the triumph of evil is for good men to do nothing.
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
#2 Re: Mosfet bias.
Hint: Have you noticed they don’t make -9v and +9v battery’s, just 9v ones?Is that + 4.7v ?
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
- pre65
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#3 Re: Mosfet bias.
OK.
I was meaning is the bias positive, as opposed to grid bias on a valve which is negative.
I'll go for the 1.3W Zener unless otherwise advised.
I was meaning is the bias positive, as opposed to grid bias on a valve which is negative.
I'll go for the 1.3W Zener unless otherwise advised.
The only thing necessary for the triumph of evil is for good men to do nothing.
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
- pre65
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#4 Re: Mosfet bias.
Would something like this (see link) be suitable for mosfet bias duties, with (for example) a 6v PSU (wall wart ?) instead of the solar panel.
http://www.theorycircuit.com/solar-powe ... r-circuit/
Or am I worrying too much about this ?
http://www.theorycircuit.com/solar-powe ... r-circuit/
Or am I worrying too much about this ?
The only thing necessary for the triumph of evil is for good men to do nothing.
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
#5 Re: Mosfet bias.
You want as low noise as possible, and I don't know if it need to be adjustable. I haven’t read the info on the amp design. I would (personally) avoid wall warts.
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- pre65
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#6 Re: Mosfet bias.
Thanks Nick. I think there are a couple of 6v transformers in a box somewhere.
Does the bias supply (fixed @ 4.7v) have much current ?
I've tried searching on the web, and checking the IXFN140N20P data sheet but I can't seem to see any figures.
http://docs-europe.electrocomponents.co ... a3b4bf.pdf
Does the bias supply (fixed @ 4.7v) have much current ?
I've tried searching on the web, and checking the IXFN140N20P data sheet but I can't seem to see any figures.
http://docs-europe.electrocomponents.co ... a3b4bf.pdf
The only thing necessary for the triumph of evil is for good men to do nothing.
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
#7 Re: Mosfet bias.
No.Does the bias supply (fixed @ 4.7v) have much current
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#8 Re: Mosfet bias.
Also the actual bias might not be exactly 4.7V. Most obvious method is set it with a preset? There won't be any DC flow thru the gate.
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
- pre65
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#9 Re: Mosfet bias.
I'm reading what you have written, but not sure what you mean.Mike H wrote:Also the actual bias might not be exactly 4.7V. Most obvious method is set it with a preset? There won't be any DC flow thru the gate.
The only thing necessary for the triumph of evil is for good men to do nothing.
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
Edmund Burke
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#10 Re: Mosfet bias.
A nice lead in to the basics of mosfet amps http://www.electronics-tutorials.ws/amp ... ifier.html
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#11 Re: Mosfet bias.
Sorry, I meant preset is simple and easy to do as there is no current flowing through the gate, so the preset only has to provide a Voltage.pre65 wrote:I'm reading what you have written, but not sure what you mean.Mike H wrote:Also the actual bias might not be exactly 4.7V. Most obvious method is set it with a preset? There won't be any DC flow thru the gate.
However the final circuit configuration may make this method completely irrelevant; what is this MOSFET being used for?
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
- pre65
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#12 Re: Mosfet bias.
This. There is a thread in projects. It's a single ended mosfet, the mosfet is the size of an ice hockey puck.
The only thing necessary for the triumph of evil is for good men to do nothing.
Edmund Burke
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Edmund Burke
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#13 Re: Mosfet bias.
A-HA!! Now I see.
OK so where it says '4.7V' at the bottom, could still be from a preset, with say 12VDC across it. Would provide a means of adjusting the ouptut DC Volts.
OK so where it says '4.7V' at the bottom, could still be from a preset, with say 12VDC across it. Would provide a means of adjusting the ouptut DC Volts.
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
- pre65
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#14 Re: Mosfet bias.
Yes.
I'm not au fait with mosfets (or transistors) so this is a steep learning curve.
The 4.7v zener idea appealed to me as a fit and forget option.
Any alternative suggestions welcome.
I'm not au fait with mosfets (or transistors) so this is a steep learning curve.
The 4.7v zener idea appealed to me as a fit and forget option.
Any alternative suggestions welcome.
The only thing necessary for the triumph of evil is for good men to do nothing.
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
Edmund Burke
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#15 Re: Mosfet bias.
Understandaby, and would be great IF the actual MOSFET gate bias Voltage matches exactly.pre65 wrote: The 4.7v zener idea appealed to me as a fit and forget option.
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."